Despite improvements in preventive techniques, infections remain as one of the most common serious complications of cancer therapy. The BCRC has continuing research programs designed to improve the therapeutic approach to these infections. The setting of new fever during granulocytopenia represents infection in approximately 70 percent of cases with bacteremia occurring in 20 percent, thus necessitating the prompt empiric use of broad-spectrum, bactericidal antibiotics. The BCRC has helped to form and participate in a multiinstitutional international antimicrobial therapy trial. Patients were randomly allocated to receive one of three antibiotic combinations as part of a prospective controlled trial which included 625 patient-trials (253 from the BCRC). Although each of the three regimens was efficacious for the majority of infections, carbenicillin plus gentamicin was found to be superior to cephalothin plus gentamicin for P. aeruginosa bacteremia, superior to carbenicillin plus cephalothin for E. coli, and equivalent to the other two regimens for Klebsiella and S. aureus bacteremia. In addition, the cephalothin plus gentamicin combination produced significant renal dysfunction in 15 percent of patients compared to 2-3 percent for the other drug combinations. It was concluded that under the circumstances of this study, carbenicillin and gentamicin was the combination of choice.